1. Field of the Invention
This invention relates to the production of anhydrous aluminum chloride from aluminous raw materials and, in particular, to an improved process of producing this material from acid leach-derived aluminum chloride hexahydrate (ACH) by dehydration of the ACH followed by reductive chlorination.
2. Brief Description of the Prior Art
It is known that anhydrous aluminum chloride can be electrolytically reduced at low temperatures of about 700.degree.-750.degree. C. to produce aluminum and chlorine with less energy consumption than with Hall technology reduction of alumina. Many processes have been proposed to economically produce anhydrous aluminum chloride in order to take advantage of the energy savings. Aluminum chloride useful in electrolytic cells must be essentially free of moisture. In addition, it must be of high purity.
U.S. Pat. No. 4,264,569 teaches a process for producing anhydrous aluminum chloride for use in electrolytic cells wherein the ACH is heated at a temperature range of 200.degree.-450.degree. C. until it is substantially dehydrated and thereafter reacting the dehydrated material in the presence of a gas mixture of chlorine, carbon monoxide, carbon dioxide and hydrogen to produce gaseous anhydrous aluminum chloride.
Heretofore, however, the prior art has failed to recognize the advantages to be obtained by selecting an acid-leach derived ACH.